Toilet tank



FIG. 1 is a perspective view of a toilet tank showing our new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is a first side view thereof, the opposite side being a mirror image of the side shown; and,

FIG. 5 is a first end view thereof, the opposite end being a mirror image of the end shown. 

CLAIM The ornamental design for a toilet tank, as shown and described. 